Hitherto, there is known the art capable of improving workability when assembling an engine for a vehicle, for example, by having a floor surface of a carriage for loading and carrying an assembled engine formed at the same level as a floor surface of a passage for operations (for example, see patent reference 1).
There is also known the art where a secondary traveling line is connected to an upstream side and a downstream side of a primary straight traveling line to form a circulation line so as to have the carriage driven by friction drive means throughout the carrying route, wherein the assembling process is performed in such a manner that parts and the like are assembled into the carried article while the carriage is conveyed at a constant speed on the primary traveling line, and the carriage is conveyed at high speed on the secondary traveling line and returned to the original position thereof (for example, see patent reference 2).
Patent reference 1: Japanese patent application publication No. 2004-196114
Patent reference 2: Japanese patent application publication No. 2002-240707